Tank trucks have been widely used for a variety of purposes. The invention is concerned particularly with the transportation of fluids which tend to settle during storage or which may freeze or for other reasons may require agitation. One example is drilling mud used in oil fields for filling well holes. Drilling mud has a tendency to settle during storage and in some locations will freeze in the tank, which is of course unacceptable. In Alaska, for example, I have seen oil well drilling mud freeze in some portions of a tank truck in less than an hour. An important objective of the invention is to provide a practical means for agitating a fluid product such as drilling mud while being transported by tank truck. Another objective is to provide a tank truck which is versatile with respect to the fluids that can be transported so that it is capable of use for any application desired. Thus, one day it may used for drilling mud but the next day for water and on another occasion for transporting crude oil or other petroleum product. Tank trucks previously available have either been limited as to the type of product they can carry or have not been satisfactory for rapid conversion from one type of product to another. Prior tank trucks moreover do not provide a good means for agitating a thick or semi-fluid material such as drilling mud or for distributing heat from a heater to different parts of the tank as desired. The drilling mud therefore may, under certain circumstances, have a tendency to settle or become frozen around the edges. Previously, once the freezing process started it interfered with the agitator operation and this in turn allowed the material to freeze at an even faster rate.
In view of these and other shortcomings of the prior art, it is an object of the invention to provide an improved tank truck capable of rapidly loading and transporting a variety of fluids including water, petroleum, fuel oil, drilling mud and the like.
Another object is to reduce the cleanup time when the tank truck is converted from one product such as drilling mud to another product such as petroleum.
Another object is to provide a tank truck of the type described which is easy to work on and requires few if any tools for routine operation and cleanup by the operator.
Another object is to provide improved agitation capable of moving a fluid product within the tank in any one of several modes to produce currents in different directions and when a heater is present to carry the heat in different directions as desired.
A further object is to enable the agitators to be removed and replaced quickly and efficiently and preferably without the use of special tools.
Yet another object is to provide an improved tank truck of the type described in which the tank is easy to enter and includes a heater.